Electrical insulators of the type involved are conventionally formed by assembling and permanently securing together, a body portion of dielectric ceramic material, a metallic cap fitting over and about the hollow body portion, and a metallic stem having one end fixed within the cavity of the body and extending therefrom. The protruding end of the stem is enlarged to fit a correspondingly-shaped recess in the outer end of the cap of a contiguous insulator so that when desired, a string of such insulators may be separably assembled in aligned relation.
The cap and its stem may be rigidly attached to the dielectric body in various ways, the usual procedure being by a seal of mortar. The mortar is prepared by mixing cement with water in suitable proportions and which, before setting, is introduced into the respective cavities of the cap and body portion. The cap is then positioned over and about the body and one end of the stem is inserted into the mortar in the cavity of the body. The parts are then maintained in proper relation in a suitable jig or mounting apparatus until the mortar hardens.
Alternatively the mortar containing the correct amount of water, may be pre-mixed, then added to the interstices between the insulator parts while these parts are held by jig means in their correct centralized relation. Advantageously the mortar may be vibrated not only during mixing but also after emplacement between the parts being permanently connected.
The prior art procedures above outlined all have the same drawback, namely, that the mortar is not added to the cavities of the insulator parts until after it has been mixed. Thus there is an unavoidable loss of time which prevents adaptation to continuous production line operations. Such procedures also result in a partial setting of the mortar before the parts can be brought into assembled relation.